Tribbles are fictional alien species in the Star Trek universe who first appeared in the episode titled "The Trouble with Tribbles". They are depicted as small, furry, soft, gentle, attractive, and slow-moving, and they usually produce a soothing purring or cooing sound when stroked, all of which are endearing traits to humans, Vulcans, and their hybrids. However, because tribbles reproduce incredibly fast, and consume exponentially larger and larger amounts of food as they multiply and crawl stealthily from one place to another, Starfleet considers them dangerous organisms and forbids their transportation. The Klingons, in whose presence tribbles produce a convulsive, shrieking reaction, go as far as to consider them "mortal enemies", as stated in the Star Trek: Deep Space Nine episode "Trials and Tribble-ations".

While appearing in only four episodes and briefly in four of the Star Trek movies, they are one of the most popular and well-known species featured in the Star Trek universe, fairly well known even to casual followers of the series. In 2006, two tribble props from "Trials and Tribble-ations" were auctioned for US $800 to $1,200.[1]

Because of their popularity, the core episodes featuring tribbles ("The Trouble with Tribbles", "Trials and Tribble-ations", and the animated "More Tribbles, More Troubles") were collected on a single laserdisc, "Triple Tribble Troubles". This was the only Star Trek laserdisc to contain episodes from multiple series. The Blu-Ray boxed set of Season 2 of the show used the same selection of episodes on disk 4, with the latter 2 episodes appearing as bonus features.

The expression "multiplying like tribbles" has also become commonplace in the context of science fiction or technology.[2]

A family of proteins which have a variety of roles, including involvement in the control of the cell cycle in the fruit fly, was named after these fictional animals.[3][4]

According to Star Trek canon, tribbles are native to the planet Iota Geminorum IV. They are essentially small bundles of fur with no visible external features. The fur of live-action and animated tribbles ranges from solid white to grey, speckled light to dark brown, yellow to reddish orange, and black. According to Dr.Leonard McCoy's dialogue, their only two purposes in life appear to be to eat and to reproduce, and they perform both of these functions exceptionally well. McCoy concludes that tribbles use over fifty percent of their metabolism for reproduction and that they are born pregnant. A creature that was genetically engineered to hunt tribbles is introduced in the episode of Star Trek the Animated Series "More Tribbles, More Troubles".

David Gerrold, in The Trouble With Tribbles: the Birth, Sale, and Final Production of One Episode[5] mentions that after the episode was aired, people asked him if tribbles were inspired by the flat cats of Robert A. Heinlein's novel, The Rolling Stones, which are a similar small, fuzzy creature. He writes:

Look — I thought I was telling the “rabbits in Australia” story. When rabbits were introduced to Australia, they multiplied at an incredible rate because there were no predators or natural enemies to keep them in control. It was an ecology story — and a spaceship is the perfect setting for it because a spaceshipmust bea balanced ecology.

When it came to designing the creatures though, I had to be simple — they had to be easy to build; they had to be cheap, and they had to be believable. We wouldn’t want to use rabbits for the story — we wanted something … well, gimmicky. We needed a science fiction animal. …

I had to think — what would be easy?

Holly ... Sherman had a key ring attached to a ball of pink fuzz. The more I looked at it, the more obvious it became. ...The ease with which a fluff ball could be manufactured made it a natural candidate.

The concept is an old one that predates even the Heinlein novel, since it is central to the story "Pigs Is Pigs", which was popular from its first publication in 1905 and beyond.

The name for the creatures was originally "fuzzies," but to avoid confusion with the H. Beam Piper novel Little Fuzzy, Gerrold brainstormed some nonsense words, arriving at "tribble" almost at random. The similarity of sound to that of the word "trouble" led him to attempt, unsuccessfully, to convince producer Gene L. Coon to change the title to "You Think You've Got Tribbles--?" before accepting "The Trouble With Tribbles" as the title.

A human named Cyrano Jones (portrayed by Stanley Adams), a small-time merchant, introduced a handful of tribbles to Captain Kirk's crew. Spock, who is half-Vulcan, explains that the species is not endearing to Vulcans, as they see no useful purpose for tribbles. However, he is caught petting one while claiming, "Fortunately, I am... immune to its effects."

From Klingons, though, tribbles have what appeared to be a mutually allergenic effect; when Jones approached him with one, the Klingon Korax (actor Michael Pataki) yelled, "Get out of here with that PARASITE!!!" Later, this same mutual negative reaction unmasks Arne Darvin (actor Charlie Brill) as a surgically altered Klingon who had tried to ruin the Sherman's Planet Development Project. According to non-canon sources,[which?] this is because Klingons and tribbles both have keen senses of smell (one such source[which?] says that tribbles find food by scent) and each subsequently finds the other's "stench" revolting and upsetting.

Tribbles returned in the Star Trek: The Animated Series (also known as The Animated Adventures of Gene Roddenberry's Star Trek) episode "More Tribbles, More Troubles". This time, the tribbles Cyrano Jones brings had been genetically altered so they would not reproduce when fed, but instead simply grow larger. They inevitably grow to amazing sizes and fill up the ship. David Gerrold, who also wrote this story, originally pitched it for the third season of Star Trek: The Original Series, but it was rejected by the producer Fred Freiberger who apparently hated the comedic elements that some writers had included in certain episodes.

In "When the Bough Breaks", it appears that one of the little girls that was kidnapped has a small stuffed toy tribble with eyes. It is not the exact form of a tribble, as they don't have visible eyes, but it no doubt is a small homage to them due to the extreme similarities. The tribble toy ends up being stuck to Captain Picard's back at the end of the episode when the child hugs him for saving them.

In "Trials and Tribble-ations", the Deep Space Nine characters were edited into scenes from different episodes of the original series cast.

In this episode, the crew of the USS Defiant encounter tribbles when they accidentally travel back in time and participate in the events of "The Trouble With Tribbles". Worf reveals that the tribbles Scotty beamed aboard the departing Klingon cruiser were brought back to Klingon territory where they quickly spread off the ship and began multiplying. While Scotty had intended it to be a harmless joke, the tribbles spread like locusts and devastated the ecosystems of planets across the Klingon Empire. Tribbles did so much damage to the Klingon Empire's agricultural base that they were considered "a mortal enemy of the Empire", and ultimately they were hunted down and exterminated. Specially trained warriors were sent to kill every tribble in existence, and an armada of Klingon vessels obliterated the tribble's homeworld, planet number IV of the Iota Geminorum star system. Klingons are unique among Star Trek's races in their extreme hatred of the creatures as "an ecological menace". The feeling was apparently mutual, because tribbles emit a loud shrieking noise instead of their normal soothing purr in the presence of Klingons. Deep Space Nine Security Officer Odo, amused by the irony of the fierce Klingons hunting the gentle tribbles, dryly remarked, "Another glorious chapter in Klingon history. Tell me, do they still sing songs of 'The Great Tribble Hunt?'" A number of tribbles were accidentally brought back to Deep Space Nine from the past, and the species was re-established, undoing the Klingon Empire's efforts to bring about the extinction of the tribble.

The date of first contact with tribbles has never been established in canon. Chronologically speaking, the earliest known appearance of tribbles was in the 2003 Star Trek: Enterprise episode "The Breach" (which takes place in 2152) in which Doctor Phlox uses them as food for his medicinal pets in Sick Bay. Hoshi Sato, a human, sees a tribble being utilized by Phlox. Phlox remarks that their populations would be out of control if it was not for their homeworld's high reptilian population.

Tribbles are used as a form of trade in the computer game Star Trek: Armada II and as a weapon (transported to the enemy's ship to multiply there and fill it) in Star Trek: Starfleet Command: Orion Pirates. In Star Trek Online, tribbles are used as a healing device by petting them while on away missions. Tribbles can also be fed and bred to create rare tribbles with unique abilities such as increasing damage dealt by the player or increasing the player's damage resistance.

In the video game Elite and the play-alike Oolite tribble-like creatures called Trumbles are repeatedly offered to players once their score exceeds 6553.6 credits. Once acquired they then breed, eat all cargo and fill up the complete cargo space, later even running all over the screen. They can be destroyed by flying close to the sun.

Season 1, Episode 10 of the animated series My Little Pony: Friendship is Magic, entitled "Swarm of the Century", features small parasitic creatures called parasprites. Considered to be disarmingly adorable by most of the inhabitants of Ponyville, they rapidly multiply and soon the town is completely overrun. Although parasprites have wings and can fly, they produce a similar "purring" sound and have many other qualities of Tribbles. According to the developer of the show, Lauren Faust, "It (the episode) was initially conceived as just a story about a plague of locust-like creatures, but the parallels to Tribbles became apparent pretty fast. I'm a huge Star Trek dork, so we went with it." [8]